For any individual who is physically active and trains over four times a week, let alone striving for performance, immune health is something that should not be over looked.

There is a lot of evidence that demonstrates how strenuous exercise, if not managed well through rest, recovery and nutrition can depress the immune system, hindering performance outcomes. Thus, the average baseline for immunity does not suffice and more attention is required in maintaining a healthy system.



Regularly monitoring the levels of Iron, Ferritin and B12, thyroid function, Vitamin D and white cell count in the blood is important to understand how the immune system is functioning, especially during high volume and/or intensity training blocks. With this knowledge, strategies can be implemented to ensure the best possible health for each athlete.

One of the main challenges, especially for UK based athletes due to the limited/lack of sunshine, is to ensure enough Vitamin D, therefore regular monitoring is advised. Vitamin D is a very important nutrient when it comes to immune function and mood. Luckily it is very easy to supplement through the winter months. For individuals who are highly active a serum Vitamin D level of above 75 is recommended, anything under a should be supplement required – if levels are below 50 then aim for 4000 iu a day; if levels are 50-75 then aim for 1000 iu a day. 



In order to optimise immune health and recovery in active individuals, it is important to obtain sufficient sleep each night, ideally around 8 hours. Few people know that Growth Hormone, responsible for physical repair is at its highest around 12-2am. Aiming to get to bed early enough will ensure that you make the most of this. To minimise sleep disruption aim to turn off laptops and phones at least 30 minutes before your preferred sleep time, as the blue light interferes with melatonin production - a key hormone required for quality sleep. 



Good nutritional practices are necessary for performance and immune health; however, it is not just about what you eat but also about maintaining hydration. Good hydration should not be ignored as it encourages the production of saliva which is the bodies first line of defense. Herbal tea, no added sugar squashes and flavoured waters can all encourage the consumption of fluid to maintain hydration.

With regards to nutrition it is vital to consume a sufficient number of carbohydrates throughout the day, particularly in high intensity or volume training blocks. This not only ensures appropriate fuelling for the body but also helps prevent the suppression of the immune system, which can be a result of inadequate fuelling. 

As a recommendation aim for a third of a plate at every meal of wholegrain nutrient dense carbohydrates such as sweet potato, pasta, rice etc. on training days and a quarter plate on non-training days.

In addition, these whole grains along with beans and pulses are prebiotics, nutrients necessary for the correct action of probiotics to encourage a positive environment for gut flora to thrive, helping to boost immune health.

Lastly, in times of high training or competition there is evidence to suggest taking a 12 week course of high strength probiotics can prevent the incidence of upper respiratory tract infections in athletes. 

 Gain insight into your immune health and other key markers for performance with an Endurance Test.

This blog was written by Renee McGregor, Performance and Clinical Dietitian @mcgregor_renee